Zirconocene naphthalene complex

ABSTRACT

1. THE COMPOUND (($$C5H5)2ZR.CR10H8))N WHEREIN &#34;N&#34; DESIGNATES THAT SAID COMPOUND IS POLYMERIC.

United States Patent 3,839,381 ZIRCONOCENE NAPHTHALENE COMPLEX Guido P. Pez, Boonton, N.J., assignor to Allied Chemical Corporation, New York, N.Y.

No Drawing. Continuation-impart of application Ser. No. 180,144, Sept. 13, 1971, now Patent No. 3,776,932. This application Apr. 26, 1973, Ser. No. 354,830

Int. Cl. C07f 7/00 US. Cl. 260-4293 1 Claim ABSTRACT OF THE DISCLOSURE Zirconocene naphthalene of formula is prepared by low temperature reaction in an ethereal solvent between an alkali metal naphthalene and a dihalogenide of dicyclopentadienyl zirconium.

The complex has utility as an absorbent of nitrogen.

CROSS REFERENCE TO RELATED APPLICATION This application is a continuation-in-part to my US. application Ser. No. 180,144 filed Sept. 13, 1971, now US. Pat. No. 3,776,932.

BACKGROUND OF THE INVENTION I. Field of the Invention This invention relates to a metal-organo complex having the structure:

II. Description of the Prior Art In the early nineteen fifties a new class of organo metallic compounds was discovered, starting with dicyclopentadienyl iron or ferrocene. Analogous compounds were soon prepared, similarly complexing a great many of the transition metals. Particular attention was focused on the titanium complex, reported to be dicyclopentadienyl titanium, and also referred to as titanocene.

In 1966 Watt and Drummond believed they had produced zirconocene, i.e. dicyclopentadienyl zirconium II.

By 1970, it was reported (H. H. Brintzinger and I. E. Bercaw, JACS 92:21 pg. 6l82-6l85) that the titanium metal-organo complex which various investigators had isolated, was not ((C H Ti) as had been erroneously reported, but its stable isomer, the hydride 11 (C H )TiH SUMMARY OF THE INVENTION I have now found that the zirconocene prepared by Watt and Drummonds method is actually the hydride dimer [(C H )(C H )ZrH] -xC H when all air is carefully excluded; which quickly converts to an oxidized form upon exposure to air, having the Watt and Drummond infrared spectrum.

My preparative method for the true zirconocene structure may briefly be stated as follows:

An alkali metal naphthalene, generally prepared in situ but prior to the addition of the dihalogenide reactant is allowed to react in an ethereal solvent, in an inert atmosphere, and at temperatures below about 35 C. with a dihalogenide of dicyclopentadienyl zirconium. The reaction mixture is allowed to gradually warm to ambient temperatures, the solvent is evaporated, and the naphthalene sublimed, both operations being carried out under reduced pressure, and at temperatures below 40 C. The residue obtained is extracted with an organic solvent or a mixture of solvents, and the product metal-organo complex, complexed with and stabilized by naphthalene, is ob- 3,839,381 Patented Oct. 1, 1974 tained by removal of the solvent. The highly active product must be protected from oxygen.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The operations are carried out in a reaction vessel from which all air has been evacuated, or replaced with an inert atmosphere such as argon. An alkali metal, such as potassium, sodium or lithium is stirred with at least the stoichiometric amount of naphthalene in a substantially dry, oxygen-free ethereal solvent such as tetrahydrofuran (THF) or dimethyl ether. Stirring is continued at about ambient temperature until the formation of the metalnaphthalene or naphthalide solution is essentially complete, and no appreciable quantity of the elemental alkali metal remains.

The solution is now cooled to a temperature within the range of 200 C. to 35 C., preferably between 200 and 150 C. and approximately the stoichiometric quantity of the dihalogenide such as (Cp) ZrCl (dicyclopentadienyl zirconium dichloride) is added. Additional ethereal solvent is generally added at this point. Although not essential to the process, it serves to rinse the last of the charge of solid dihalogenide into the reactor.

The temperature is next raised to, and maintained within the range of -l00 and 35 C., preferably between and 70 C., for from 30 to 500 hours. Following this the temperature is raised to and maintained between -55 to 25 C. for between 2 to 100 hours, then allowed to warm to ambient temperature. This slow warming period, as well as the low temperatures employed during the reaction are features of the present invention. If prepared at ambient temperatures an inordinate amount of the isomeric hydride would be produced, and if the batch were rapidly warmed to ambient temperatures, the product yield would be adversely aifected.

The ethereal solvent and some free naphthalene are next removed by distillation and sublimation in a system from which the gaseous atmosphere has been evacuated, at temperatures below 40 C., preferably between 25 and 35 C. The remaining crude residue is solvent extracted, generally at a temperature between and ambient temperature.

The following example, in which parts are by weight, is descriptive of the novel compound of this invention and sets forth the best mode contemplated by me for its preparation.

EXAMPLE A reactor was loaded, under an atmosphere of pure argon, with solid potassium droplet sized balls (8.0 gm.), and naphthalene (26.22 gm. an excess of 19.86 gm).

With the reactor attached to a vacuum line, THF (tetrahydrofuran) solvent (500 ml.) was distilled into the reactor bulb containing the potassium and naphthalene. The mixture was stirred for a period of 24 hours to insure complete dissolution of the metal. This green potassium naphthalene solution was subsequently frozen by cooling with liquid nitrogen. Then (1rC H ZICl powder (29.90 gm.) was added to the frozen solution together with fresh THF, so as to make a total solution volume of about 1 liter. When addition was complete, the apparatus was allowed to warm to --1l1 C. where it was kept (with continual and vigorous agitation) for a period of 3 hours. The temperature was then raised to 80 C., where it was kept with continual stirring for 2 weeks. When at 1ll C. and in the initial period at 80 C. the solution color was a light heterogeneous brown. After 2 Weeks of stirring the color had changed to a browngreen. Subsequent warming, for 2 days at 45 C., /2

day at 35 C., 1 hour at 20 C. produced a deep green homogeneous solution.

The deep green solution mainly contains Zirconoeene naphthalene, together with some free naphthalene. The following extraction procedure for Zirconoeene naphthalene was used. All the solvent THF and some of the free C H were removed by vacuum distillation at 20 C. over a period of 8 hours. Fresh THF solvent (700 ml.) was then added to re-form the deep green solution. This was then filtered, as quickly as possible, by applying suction to draw the solution through a glass frit aided by pressure of argon in the reactor. The extraction was repeated with a second 700 ml. of THF. The green zirconocene naphthalene in solution was evaporated to dryness and then washed with 3X 150 ml. lots of toluene. Zirconoeene naphthalene as a black, apparently crystalline, product was left in the recator receiver flask. Yield, 13.8 gm, 40% based on the weight of (Cp) ZrCl employed.

Characterization of Zirconoeene Naphthalene The product was a coarse black, apparently crystalline, powder. Samples of the material have been kept, under argon, at 2030 C. without noticeable decomposition. However, the green solutions thereof formed in various solvents, e.g., THF (very soluble), benzene, toluene, mesitylene (slightly soluble) do not keep at 20 C., but rearrange to various blue-colored, relatively inactive zirconocene hydride species.

Elemental Analyses.Found: C, 70.00; H, 4.86; Zr, 24.99. Theory: C, 68.72; H, 5.15; Zr, 26.12 for m m m s- Molecular Weight Measurements These measurements were attempted for solutions in THF, using the isopiestie method. In this solvent, the substance appears to be polymeric with a molecular weight greater than 2000.

Infrared Spectrum IR. spectrum of the material is in excellent agreement with the structure:

I: (1r'C H Zl- C H Sharp (7I"'C5H5) metallocene bands appear at 795 and 1010- On this is superimposed the apparently unperturbed infrared spectrum of naphthalene. Only a very weak absorption at 13001400 cm. indicative of hydride impurities, is observed.

NMR Spectrum The spectrum of the Zirconoeene naphthalene in THF solutions contins a complex set of partially resolved peaks in the region of 4-7 p.p.m. relative to TMS. The fully resolved spectrum of naphthalene moiety, apparently unperturbed by coordination, also appears. The NMR lines in the 4-7 p.p.m. regions are characteristic of the 1r-bOl1nd C H species. Though the spectrum cannot be interpreted in terms of a specific molecular configuration, it is consistent with what one would expect from a large polymeric (C H Zr species, containing loosely coordinated naphthalene.

Reactivity With Dinitrogen Toluene solutions of Zirconoeene naphthalene do not react with N gas at 1 atm. at 20 to C., as do similar solutions of bi-titanocene.

However zirconocene-dinitrogen complexes are formed upon exposing zirconocene naphthalene solutions to nitrogen gas under pressure of 200 psi at 20 C.

Zirconoeene naphthalene mg.) in toluene (10 gm.) was left over N gas at 200 psi. at 20 C. After one day, the green solution color turned distinct brown. This transformation into a brown, toluene soluble, material was complete after 7 days.

Infrared examination of the product showed a familiar hydride band, the 800 and 1010 cm. (broad) metallocene frequencies, and little or no coordinated naphthalene. To the brown product an excess of potassium naphthalene in THF was first added and then water. Traces of ammonia were detected in this mixture.

I claim:

1. The compound [(1rC H ZI"C! H wherein n designates that said compound is polymeric.

References Cited Watt et al.: J. of The American Chemical Society, Vol. 38, pp. 5926, 5927 (1966).

HELEN M. S. SNEED, Primary Examiner US. Cl. X.R.

$32 9 I UNITED STATES fATENT OF FICE I CERTIFICATE OF CORRECTION Patent No. 39, 38 I d October 1, 197 1 Inventor) Guido P. Pez

, It is eertified that error appears in the aBove-identified patent and that said Letters Patent are hereby corrected as shown below:

r- "1 Col umn l, line '19: "bietitanocene" should read I I --bi s-titano'cene I Column' t, line 35,. claim 1 the formula Cr H should read H 1 n 10 8n Signed and sealed thie 3rd day of December 1974.

' (SEAL) Attes tr I Mc'cbY M.- GIBSON'JR, f c. MARSHALL DANN' I Attes t in g Officer I "Commissioner of Patents 

1. THE COMPOUND (($$C5H5)2ZR.CR10H8))N WHEREIN "N" DESIGNATES THAT SAID COMPOUND IS POLYMERIC. 